1. Field of the Invention
The present invention relates generally to a screwdriver, and more particularly to a ratchet screwdriver.
2. Description of Related Art
As shown in FIGS. 1 and 2, a prior art ratchet screwdriver comprises a main body 11 which is provided with an axial hole 13 having a receiving portion 12 via which a shank 10 is engaged with the main body 11. The shank 10 is provided in the inner end with a gear 14, which is confined by a position confining plate 16 disposed in an insertion slot 15 of the main body 11. The main body 11 is fitted into a tubular housing 17 which is provided with an assembly hole 21. The main body 11 is provided with a shifter 18 and two check plates 19. The shifter 18 has a shifting knob 22 and two feet 24. The shifting knob 22 is jutted out of the main body 11 via the assembly hole 21. The position confining plate 16 is provided with an elastic piece 25 for preventing the axial displacements of the shank 10 and the position confining plate 16.
Such a prior art ratchet screwdriver as described above is defective in design because the shifter 18 cannot be easily maneuvered due to the size of the assembly hole 21 of the tubular housing 17. In addition, the check plates 19 are provided with a recessed edge 23, which is intended to facilitate the lifting of the check plates 19 without hitting the shank 10. In light of the reduction in axial area of the check plates 19, the feet 24 of the shifter 18 are vulnerable to being trapped in the recessed edges 23 of the check plates 19 at such time when the shifter 18 is pushed to one end. Moreover, there is a gap between the position confining plate 16 and the insertion slot 15, thereby resulting in an axial displacement of the position confining plate 16 or shank 10.
The primary objective of the present invention is to provide a ratchet screwdriver which is free of the deficiencies of the prior art ratchet screwdriver described above.
The ratchet screwdriver of the present invention is basically similar in construction to the prior art ratchet screwdriver, with the difference being that the tubular housing is provided with an assembly slot, and two insertion slots, and that the shifter is provided with a sliding slot to facilitate the shifting of the shifter. In addition, the check plates are provided with an inclined portion to enhance the efficiency of the check plates being actuated by the feet of the shifter. The position confining plate is provided with two guide pillars for preventing the axial displacement of the position confining plate in conjunction with two springs and the guide slot of the main body.
The features and the advantages of the present invention will be more readily understood upon a thoughtful deliberation of the following detailed description of a preferred embodiment of the present invention in reference to the accompanying drawings.